Inflatable, disposable dunnage bags comprise a relatively inexpensive and easily useable means for stabilizing cargo or freight disposed within cargo holds, cargo bays, cargo containers, box-cars, trailers, or the like, of aircraft, trucks, trains, ships, or other transportation vehicles, so as to effectively prevent the goods from being damaged which is Likely to occur when the goods are not otherwise secured or tied down within the cargo hold or the like since the goods are subjected to shifting movements within the cargo hold or bay in response to movements of the particular transportation vehicle during shipping or transport. As is well known and conventionally practiced in the transportation industry, and as is exemplified by FIG. 1, inflatable dunnage bags 10 are placed between individual, adjacent cargo items or pieces 12, or between the individual cargo pieces and the side walls 14 of the vehicle within which the cargo hold 16 is defined, in an initially deflated condition and are then subsequently inflated with, for example, compressed air to a predetermined pressure value which is of course below the bursting pressure limit of the bag. Most bags which are conventionally employed are specifically constructed so as to be capable of withstanding bursting pressure values which are within the range of 12-30 psig. As is also illustrated, sheet or board-type buffer members 18 are also sometimes placed between the dunnage bags 10 and the cargo loads 12. One type or embodiment of a conventional dunnage bag is disclosed within U.S. Pat. No. 4,136,788 which issued to Robbins on Jan. 30, 1979.
Another conventional dunnage bag similar to that of Robbins is illustrated at 10 in FIG. 2 and is seen to comprise a sealed inner plastic bladder or bag 22 which is fabricated, for example, from polyethylene, and an outer multi-layered or multi-walled paper bag 24 that serves to protect the inner inflatable bag or bladder 22 as well as to increase the burst strength characteristics of the dunnage bag 10. In the exemplary dunnage bag 10 illustrated in FIG. 2, the outer multi-walled or multi-layered paper bag 24 is seen to comprise, for example, four paper plies or layers 1,2,3,4.
Manufacture of such conventional inflatable dunnage bags typically comprises folding a predetermined length of multi-layered kraft paper onto itself and about a longitudinal axis thereof such that the edges thereof can form an overlapping longitudinal seam, not shown, which extends along the centerline of the multi-walled or multi-layered paper bag 24, the result being a multi-walled or multi-layered paper tube having opposite open ends. The sealed plastic bladder 22 is then inserted into the paper tube through one of the open ends thereof, and the tube ends are then folded over onto themselves in a predetermined manner and are subsequently glued closed thereby forming the completed dunnage bag 10.
In accordance with the particular exemplary mode of folding and sealing each end of the multi-walled or multi-layered paper bag 24, and with only one end of the multi-walled or multi-layered paper bag 24 being illustrated in FIG. 2, it is seen that each paper ply or layer 1,2,3,4 of the multi-walled or multi-layered paper bag 24 has a first end respectively denoted by the reference characters 1A,2A,3A,4A, and a second opposite end respectively denoted by the reference characters 1B,2B,3B,4B. The ends 1B,2B, and 3B of the paper plies or layers 1,2,3 are freely disposed atop each other, while the end 1A of paper ply or layer 1 is freely disposed or inserted beneath end 1B. Ends 2A,3A, and 4A of paper plies or layers 2,3, and 4 are also disposed atop each other, however, it is seen that end 2A of paper ply 2 is fixedly secured to end 3B of paper ply 3 by means of a first glue bead 26, end 3A of paper ply 3 is fixedly secured to end 2A of paper ply 2 by means of a second glue bead 28, and end 4A of paper ply 4 is fixedly secured to end 3A of paper ply 3 by means of a third glue bead 30. The outer surface of paper ply 4 is also conventionally coated with a suitable heat-sealable plastic, such as, for example, polyethylene, in order to provide the dunnage bag 10 with a predetermined amount of water-resistance, and accordingly, end 4B of paper ply 4 is disposed atop end 4A of paper ply 4 and the ends 4A and 4B may then be heat-sealed to each other by means of well-known heat-sealing techniques.
In order to inflate the interior portion of the dunnage bag 10 with a suitable compressed gas, such as, for example, air, from an external compressed air source, not shown, when it is desired to inflate the dunnage bag 10, that is, for example, for cargo securing purposes, an inflation valve 20 is provided and is heat-sealed upon the upper wall 22B of the inflatable bladder 22 such that the valve 20 is in fluidic communication with the interior of the bladder 22. It is also seen that the inflation valve 20 extends or projects through respective holes 1C,2C,3C, and 4C provided within the ends 1B,2B,3B, and 4B of the paper plies or layers 1,2,3,4 of the multi-walled or multi-layered paper bag 24 whereby the inflation valve 20 is rendered externally accessible.
It is well-known in the industry, however, that the region of an inflatable, multi-ply or multi-layered kraft paper dunnage bag, such as that exemplified and shown in FIGS. 1 and 2 at 10, which comprises the glued flap region at which, for example, the ends 2A,3A, and 4A of the paper plies 2,3, and 4 are glued and sealed together and to the ends 3B and 4B of the paper plies 3 and 4, respectively, comprises a high-stress region at which stresses, forces, and internal pressures attendant the inflation of the dunnage bag 10 are concentrated. An important factor to be considered or which is required to be addressed in connection with such multi-ply or multi-layered kraft paper dunnage bags resides in the tendency of the multi-layered or multi-ply flaps to unfold or separate not only from each other but also as an entity from the main portions or sides of the bags. The structural integrity of such region determines, in part, the burst strength of the bag 10.
It is also noted that such multi-ply or multi-layered kraft paper dunnage bags, such as that shown and exemplified in FIGS. 1 and 2 at 10, differ radically from what is known in the industry as abrasion-resistant air bags as exemplified or disclosed within U.S. Pat. No. 4,591,519 which issued to Liebel on May 27, 1986. Air bags such as those disclosed within the noted patent are used in connection with relatively light weight or low-pressure applications, such as, for example, those applications requiring working or inflation pressures of 1-3 psi, and it is seen that such air bags are constituted or constructed from first and second sheets 16 and 24 of two-ply laminated paperboard. Such paperboard is quite stiff or rigid and in effect self-sustaining whereby the air bags may be able to stand by themselves without sagging even prior to inflation of the same and disposition between cargo loads. The folded side and end sections 18 and 26 therefore do not present the same stress, force, and internal pressure characteristics or factors which are encountered in connection with the folded flaps of a multi-layered or multi-ply kraft paper bag as has been illustrated in FIGS. 1 and 2 at 10.
Another factor which determines or affects the burst strength characteristics of the dunnage bag 10 is the provision of the inflation valve 20, and more particularly, its relative location with respect to the glued flap region. The holes 1C,2C,3C, and 4C respectively defined within the paper plies 1,2,3, and 4 of the multi-layered or multi-ply paper bag 24 comprise weakened regions of the multi-layered or multi-ply bag 24. The reason for this is that the burst strength or structural integrity characteristics of the multi-layered or multi-ply bag 24 are derived from the paper plies or layers 1, 2,3,4 per se. Consequently, the provision of the holes 1C,2C, 3C, and 4C within the respective paper plies or layers 1,2,3, and 4 define discontinuities within the paper plies or layers 1,2,3, and 4 which thereby results in a decrease in the over-all structural integrity or burst strength characteristics of the dunnage bag 10.
When this factor comprising the location of the holes 1C,2C,3C, and 4C of the paper plies 1,2,3, and 4 within the region or vicinity of the glued flap region is considered in connection with the aforenoted factor that the glued flap region already comprises a high-stress region, the entire region, area, or vicinity is compromised to a predetermined extent. This is illustrated within FIG. 3 wherein the results of burst strength testing is schematically illustrated. In particular, it is noted that when the dunnage bag 10 is subjected to bursting, the bag 10 bursts along lines or locations 32 and 34 which intersect each other and pass directly through the hole regions of the inflation valve 20.
In an attempt to therefore improve the burst strength and structural integrity characteristics of the dunnage bags, it has been proposed by the present inventors to increase the relative size of, for example, the ends 2A,3A, and 4A of the papers plies or layers 2,3, and 4 of the multi-layered or multi-walled outer bag 24 in order to in effect increase the relative size of the folded and glued flap region comprising the ends 2A,3A, and 4A of the paper plies 2,3, and 4 when they are glued to each other and to the ends 3B and 4B of the paper plies 3 and 4 by means of the glue beads 26,28, and 30, as well as the aforenoted heat-sealed polyethylene coating disposed upon the external surface of the paper ply 4. However, test data has demonstrated that in view of tucked-in nature of the paper ply ends 2A,3A, and 4A with respect to or beneath the external paper ply end 4B of the bag 10, and in view of the additional fact that the glue beads 26,28, and 30 comprise cold glue beads, no significant improvement in the burst strength characteristics or structural integrity of the bag 10 was achieved. In addition, the provision of such a folded and glued flap region which is accordingly increased in size presents a logistics or location problem in connection with the inflation valve 20.
In particular, the newly proposed folded and glued flap region would extend backwardly along the surfaces of paper ply ends 3B and 4B so as to interfere with the presence or disposition of inflation valve 20. It has therefore been additionally proposed to relocate or move the inflation valve 20 in the direction backwardly or away from the folded and glued flap region, however, this likewise presents a problem for operator personnel when it is desired to inflate the dunnage bag 10. This can be more fully appreciated if reference is again made to FIG. 1. If the inflation valve 20 was moved backwardly away from the folded and glued flap region, it would then be located more internally between adjacent cargo loads 12 or between the buffer members 18 and therefore would not be as readily accessible from an external vantage point by operator personnel whereby the inflation process would be rendered substantially more difficult to perform.
Accordingly, there is a need in the dunnage air bag art to provide a new and improved dunnage air bag which in fact exhibits improved or enhanced burst strength characteristics and wherein the inflation valve thereof is still readily externally accessible to operator personnel so as to maintain the dunnage air bag inflation process relatively simple.